In Plan B Earth v Secretary of State for Transport  EWCA Civ 214 the Court of Appeal has decided that the government’s policy in favour of a third runway at Heathrow was not produced lawfully. The policy is contained in the “Airports National Policy Statement: new runway capacity and infrastructure at airports in the South East of England” (“the ANPS”), designated by the Secretary of State for Transport (“the Secretary of State”) under section 5 of the Planning Act 2008 (“the Planning Act”) on 26 June 2018. The designation of the ANPS was unlawful because the Secretary of State, in breach of section 10(3)(a) of the Planning Act, failed to have regard to the desirability of mitigating, and adapting to, climate change in the light of the United Kingdom’s commitment to the Paris Agreement, the non-carbon dioxide (“non-CO2”) climate impacts of aviation, the effect of emissions beyond 2050, and to the ability of future generations to meet their needs. In making the designation the Secretary of State had acted on legal advice that consideration should be given only to existing domestic legal obligations and policy commitments in relation to the mitigation of, and adaptation to, climate change, which did not include the 2015 Paris Agreement.
Section 5(8) of the Planning Act requires that the ANPS should explain how the Secretary of State has “taken into account” government policy and it was necessarily implicit in that obligation that the Secretary of State must indeed first have taken that government policy into account. The Paris Agreement represented firm government policy on climate change and ought to have been taken into account by the Secretary of State in the preparation of the ANPS, but was not – which was legally fatal to the ANPS in its present form. The Court of Appeal stressed that they were not making any finding that there will be no third runway at Heathrow, nor that a national policy statement supporting this project is necessarily incompatible with the UK’s commitment to reducing carbon emissions and mitigating climate change under the Paris Agreement. What the Government now had to do was to reconsider the ANPS in accordance with the clear statutory requirements that Parliament has imposed, including taking account of government policy – and its international commitments under the Paris Agreement.
The Court of Appeal also found the Divisional Court erred by failing to give reasons for rejecting Friends of the Earth’s argument on the non-CO2 climate impacts of aviation and the effect of emissions beyond 2050, having regard to the ability of future generations to meet their needs. In line with the precautionary principle, which was well established under international law, these impacts also needed to be taken into account by the Secretary of State.